CHEMISTRY COMMUNITY

Lauren Bui 1E

i dont think we need to know buffer solutions. the final is cumulative so everything from the notes is fair game!

Lauren Bui 1E

the least electronegative atom is typically the central molecule. hydrogens will always be on the outside since they can only form one bond. make sure to know specific trends (such as how carbon always wants to make 4 bonds to keep the FC at 0)

Lauren Bui 1E

there are 6 atoms with lone pairs in edta that can bond to other molecules or ions

Lauren Bui 1E

Why is formic acid (HCOOH) stronger than acetic acid (CH3COOH)?

Lauren Bui 1E

pKa and pKb measures the strength of an acid or base respectively, whereas pH specifically measures the concentration of hydrogen ions in solution

Lauren Bui 1E

first convert the moles of the solution into moles of H+ or OH- depending on if it is an acid or base, respectively, using the molar ratios. then find the molarity of the solution. plug the molarity into pOH = -log[OH-] or pH = -log[H+] if it is a base, you will need to subtract to get pH: 14-pOH = pH

Lauren Bui 1E

2 of the 4 oxygen atoms have a -1 formal charge in oxalate. Does this play a role in deciding where the binding sites are?

Lauren Bui 1E

when you are given a chemical formula, how do you draw the right structure to tell if it is a chelate? how can you tell?

Lauren Bui 1E

Is there a rule for differentiating between mono, bi, and polydentates? What is the relationship between mono/bi/polydentates and lone pairs as well as charges on molecules with lone pairs?

Lauren Bui 1E

Why is oxalate bidentate?

Lauren Bui 1E

i believe both have ligands. If the coordination compound has a net charge, the compound is called a complex ion.

Lauren Bui 1E

yes, memorizing the names of ligands is important because we will probably be asked to name compounds on our final

Lauren Bui 1E

Hi, can someone please explain 6A.3? Thanks!

Lauren Bui 1E

can someone please explain how to do 9c.3 on the homework? thank you!!

Lauren Bui 1E

can someone please explain what a bronsted acid is?

Lauren Bui 1E

larger molar mass means a larger boiling point

Lauren Bui 1E

i dont think so. I think everything after the midterm up to sigma and pi bonds will be on the test.

Lauren Bui 1E

why do lone pairs have to be across from each other if there are multiple?

Lauren Bui 1E

How does repulsion play a role in the VSEPR model and how is it calculated?

Lauren Bui 1E

this was helpful, thank you!

Lauren Bui 1E

I believe this would make the shape bent. For example, both H20 and SO2 have lone pairs on the central atom; thus, the shape is bent.

Lauren Bui 1E

The bonds will be covalent because sulfur and oxygen are both gases. the shape will be bent because there are 18 valence electrons and a lone pair will be added to sulfur.

Lauren Bui 1E

Are we expected to memorize bond angle values? How can you tell that H20 has a bond angle of exactly 104.5?

Lauren Bui 1E

distorting refers to rearranging the electron cloud. smaller, highly charger cations cause distortion, while larger atoms (with larger electron clouds) get distorted

Lauren Bui 1E

More negatively charged anions typically means there is a bigger electron cloud. Since it is larger, it can be more easily distorted; thus more polarizable.

Lauren Bui 1E

In resonance structures, you should take the average of the bonds so they are equivalent

Lauren Bui 1E

some elements, especially beyond the 3rd period, can have an extended octet (aka hypervalency). for example, in the 4s block, the 3d is not full yet and can accept more electrons.

Lauren Bui 1E

How can you tell what the smallest cation is? Is it based on charge or size/atomic radii or something else?

Lauren Bui 1E

Yes, these are equations for light only (no mass is involved)! If you are measuring wavelike properties (for things with mass), use de broglie's equation.

Lauren Bui 1E

If an atom does not satisfy the octet rule, it means there are less than 8 electrons (i.e. the first 4 elements of the periodic table). An expanded octet refers to when there are more than 8 electrons; these are also known as exceptions to the octet rule.

Lauren Bui 1E

Is there a strategy for drawing the lowest energy lewis structure or do you have to guess and check? Are there any tips for rearranging the structure to have the lowest formal charge?

Lauren Bui 1E

What is the relationship between bond length and bond strength? and is there a reason for this relationship?

Lauren Bui 1E

When drawing a lewis structure, how do you determine which atom goes in the center?

Lauren Bui 1E

I wouldn't focus on solving for the actual affinity quantity, although I'm not 100% sure. I think it is definitely important to understand the conceptual ideas.

Lauren Bui 1E

For chromium and copper, a completely full (d10) or half full (d5) d sub-level is more stable than a partially filled d sub-level. As a result, an electron from the 4s orbital is excited and rises to a 3d orbital, because this reduces the total energy

Lauren Bui 1E

metals tend to form cations and nonmetals tend to form anions. metals tend to lose electrons to achieve noble gas configuration, because they typically have 1, 2, or 3 electrons. because nonmetals have 5, 6, or 7 electrons in their valence shell, it requires less energy to gain the necessary electro...

Lauren Bui 1E

I believe Dr. Lavelle said we did not need to use the F orbital for this class, so I would focus on the s, p, and d orbitals

Lauren Bui 1E

I think it refers to electrons that are not paired with a single atom or covalent bond.

Lauren Bui 1E

In the s-orbital, electorns have no angular momentum (l = 0), so they're distributed around the nucleus instead of circulating it. In p-,d-, and f- orbitals, electrons have angular momentum (l>0), and the spherical movement creates nodal planes.

Lauren Bui 1E

I think it would be helpful to know the order from shortest wavelength to longest wavelength (gamma, x-ray, UV, visible, infared, radio).
This is what I was told in one of the workshops at least :)

Lauren Bui 1E

Is it important to know how to derive this equation? If so, how do you do that?

Lauren Bui 1E

Where does the angular momentum quantum number come from?

Lauren Bui 1E

I don't think so. I wouldn't focus too much on it

Lauren Bui 1E

yes it can be used to calculate the energy necessary to remove an electron, but be sure to read the problem closely

Lauren Bui 1E

You can use dimensional analysis to set up a conversion from Angstroms to another SI unit, just like you would from one SI unit to another.

Lauren Bui 1E

From my understanding, the threshold energy should vary for different elements

Lauren Bui 1E

When do I use De Broglie's equation?

Lauren Bui 1E

Molarity (M) is the number of moles of solute per liter of solution whereas molality (m) is defined as the number of moles of solute per kilogram of solvent, not solution.

Lauren Bui 1E

the actual yield must be a given value or a value found from an experiment! if you're asked to find the %yield, the question will typically give you the actual yield value

Lauren Bui 1E

That clears things up a lot! Thank you :)

Lauren Bui 1E

you should use exact values from the periodic table and avoid rounding or using sig figs until the very end. this will minimize rounding error :)

Lauren Bui 1E

I think it would be beneficial to memorize the most commonly seen compounds, just to be safe :)

Lauren Bui 1E

I usually begin to balance an equation by starting from the left side of the reactants side. So I first would balance sulfur, then hydrogen, etc. In this case, sulfur would be balanced, but by adjusting the hydrogen levels, you would have to go back and adjust the level of sulfur. This method still ...

Lauren Bui 1E

What exactly are formula units?

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